As the anticonvulsant plasma level of diazepam (DZP) after intravenous injection is maintained only for a short period, it is profitable to administer DZP as an intravenous infusion. It has, however, been claimed that DZP cannot be mixed with dextrose injection as DZP would precipitate. As this is in contrast to our clinical experience we added DZP of various brands to dextrose injections. A precipitate was in fact found in dextrose injections containing Valium and Stesolid whereas Diazepam A.L. was not only slightly cloudy. The concentration of DZP was, however, the same in all the samples and corresponded to the calculated concentration. The precipitate in the solutions with Valium and Stesolid which did not pass the filter must therefore be due to additives, most probably benzoates. On the basis of these findings and our clinical experience of this mode of administration we recommend the infusion method as one of the most effective in the acute treatment of status epilepticus.